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Converting Single to Dual Circuit Brakes

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  • Converting Single to Dual Circuit Brakes

    This is something that I have been thinking of doing for a while as I'm not a fan of single circuit systems after suffering brake failure on a rally but had left it as is because it was working. Roll on to the winter checks and I was dismayed to see that the master cylinder reservoir was almost empty. On investigation it became obvious that the master cylinder had failed and the fluid leaked into the servo. That combined with not being convinced that the servo was working at its best I decided to bite the bullet and convert the system to dual circuit using a TR6 servo and master cylinder. Having gathered all of the required parts we started the process by removing the pedal box so that we could fit the new servo. I'll start posting photos as we make progress...
    Mk2 SWB Marina Roadster with a 2.0L Pinto built in 1986

  • #2
    I suffered the same problem with JRR 929 D with the remote servo emptying the master cylinder giving the engine a mixture of petrol and brake fluid to run on.
    Over the years I had competed on rallies and Landrover trials with single circuit brakes without problems.


    • #3
      I think converting to twin circuit is a good plan. After losing all the fluid from the rear brakes on Bluebelle when towing a caravan, I was glad the front ones were working. I don't think I would be confident with single circuit now.


      • #4
        So I've managed to get the servo and master cylinder fitted to the pedal box but it was tight up against the side panel when I trial fitted it so a had to cut a relief into the stiffening strip. Had trouble disconnecting the pipes from the 4 way joiner, managed to save the front pipes but the rear one was to bent to remake the end so I've had to remove it and make a new one.
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        This gallery has 5 photos.
        Last edited by andyf; 30-01-23, 02:01 PM.
        Mk2 SWB Marina Roadster with a 2.0L Pinto built in 1986


        • #5
          Hi Andy
          If you still have the old servo can you confirm that it has a seal plus a retainer cup in the front face of the servo[where the push rod exits] Thanks Alan